1. Field of the Invention
The invention relates to an ozone generator with a tubular outer electrode and a plurality of inner electrodes which exhibit a dielectric layer on their surface facing the outer electrode, means for spacing the inner electrodes from the outer electrode for forming an annular discharge gap and means for electrically connecting all electrodes to an alternating current source.
Ozonizers of this type are known, for example, from Swiss Patent Specification No. 648,534.
2. Discussion of Background
The increasing use of ozone for chemical and physical purposes has led to the ozone tube, which is based on work by Siemens, being decisively improved in technical and economic respects in the recent past. Thus, it is proposed in U.S. Pat. No. 2,811,217, to increase the ozone yield by means of the fact that particular characteristics of the ozonizer (frequency of the feed voltage, dielectric constant of the dielectric material, amplitude of the feed voltage, thickness of the dielectric layer and size of the discharge gap) must comply with particular laws.
For the same purpose, special cooling measures are proposed in other publications for increasing the ozone yield, thus, for example, in addition to the liquid cooling of the outer electrode, the internal cooling of the high voltage electrode with gas or liquid in German Offenlegungsschrift No. 2,357,392, or the intermediate cooling of the ozone-enriched feed gas in the case of cascaded ozonizers in German Offenlegungsschrift No. 2,436,914.
It is generally known that the mean temperature in the discharge gap can be lowered by reducing the discharge gap width in a tubular ozone generator. It can be demonstrated theoretically and experimentally that the mean temperature in the discharge gap is proportional to its gap width.
A low temperature in the discharge gap is desirable since this significantly increases the efficiency of ozone generation.
At present, discharge gap widths of around 1 mm are the state of the art. With a further reduction in gap width, the limits of geometric tolerances of the metal and dielectric tubes used are reached. Particularly in the case of relatively great tube lengths, a further reduction in gap width is limited by the ever present bending of the dielectric and metal tubes.